1. Field of the Invention
The present invention generally relates to belt drives for small vehicles, such as all terrain vehicles, for instance. More particularly, the present invention relates to cooling arrangements for such belt drives.
2. Description of the Related Art
Small all terrain vehicles generally feature a frame assembly that supports a fuel tank and a seat. An engine is generally positioned within an engine compartment defined by the frame assembly and is located generally beneath the seat and/or fuel tank. In conventional small all terrain vehicles, the frame assembly is supported by at least one front wheel and two rear wheels. The wheels are driven by a shaft, belt or chain drive configuration. Depending upon the drive configuration, the vehicle can be driven by two of the wheels or all of the wheels.
In some arrangements, a continuously variable transmission (CVT) can be used to transfer power from the engine to a final drive assembly. Such transmissions can employ a drive belt that is wrapped around a pair of variable diameter pulleys. During operation, such transmissions generate a great deal of heat. Due to the nature of the CVT, heat can decrease performance and life of the CVT.
Accordingly, cooling systems have been developed for introducing air into a chamber in which the belt and pulleys are positioned. The air circulates within the chamber before being exhausted back into the atmosphere. In most arrangements, the air is exhausted in a forward direction at a location generally positioned beneath the seat. This position reduces the likelihood that water being splashed by the rear wheels will work its way into the transmission through the exhaust duct. This arrangement, however, has a disadvantage in that the air, which has been heated by the transmission, is exhausted in close proximity to an operator of the vehicle. This is undesirable for many reasons.
Thus, a cooling system for a CVT is desired in which the exhausted air is directed away from an operator while the likelihood of water being thrown back through the exhaust ducting is greatly reduced.
Accordingly, one aspect of the present invention involves an all terrain vehicle comprising a frame assembly and an engine unit mounted to the frame assembly. A pair of rear wheels support the frame assembly. A seat is disposed generally above at least a portion of the engine unit. The engine unit comprises a continuously variable transmission. The transmission comprises an input pulley, an output pulley and an endless loop connecting the input pulley and the output pulley. The transmission is disposed within a chamber that is defined at least in part by a transmission cover. A cooling system cooperates with the chamber to introduce cooling air to the chamber and to remove cooling air from the chamber. A storage compartment is disposed at least partially beneath the seat. A partition defines an exhaust chamber within a portion of the storage compartment. The cooling system comprises an exhaust duct. The exhaust duct communicates with the exhaust chamber and the exhaust chamber communicates with the atmosphere.
Another aspect of the present invention involves an all terrain vehicle comprising a frame assembly with a seat supported by the frame assembly. An engine unit is mounted to the frame assembly in a location generally under the seat. The engine unit comprises a belt drive assembly. A cooling system cooperates with the belt drive assembly. The cooling system comprises an exhaust duct that extends rearward from the belt drive assembly. An exhaust chamber is disposed rearward of the engine unit and is elevated above the belt drive assembly. The exhaust duct terminates in the exhaust chamber. A storage compartment is positioned forward of the exhaust chamber and is at least partially positioned under the seat.